org.apache.lucene.search.spans

Class EmptySpans

Object

EmptySpans

All Implemented Interfaces:

Spans

public class EmptySpans
extends Object
implements Spans

Expert: An empty list of spans, suitable for ORing with other lists.

Field Summary

Fields

Modifier and Type	Field and Description
static EmptySpans	theInstance Static instance; there's no need to ever create a new EmptySpans()

Constructor Summary

Constructors

Modifier	Constructor and Description
private	EmptySpans() Don't create a new instance... use theInstance.

Method Summary

Modifier and Type	Method and Description
void	collectTerms(Set terms)
int	doc() Returns the document number of the current match.
int	end() Returns the end position of the current match.
Explanation	explain() Returns an explanation of how the score was arrived at.
boolean	next() Move to the next match, returning true iff any such exists.
float	score() Returns the score of the current match.
boolean	skipTo(int target) Skips to the first match beyond the current, whose document number is greater than or equal to target.
int	start() Returns the start position of the current match.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

theInstance

public static EmptySpans theInstance

Static instance; there's no need to ever create a new EmptySpans()

Constructor Detail

EmptySpans

private EmptySpans()

Don't create a new instance... use theInstance.

Method Detail

next

public boolean next()
             throws IOException

Description copied from interface: Spans

Move to the next match, returning true iff any such exists.

Specified by:

next in interface Spans

Throws:

IOException

skipTo

public boolean skipTo(int target)
               throws IOException

Description copied from interface: Spans

Skips to the first match beyond the current, whose document number is greater than or equal to target.

Returns true iff there is such a match.

Behaves as if written:

   boolean skipTo(int target) {
     do {
       if (!next())
              return false;
     } while (target > doc());
     return true;
   }
 

Most implementations are considerably more efficient than that.

Specified by:

skipTo in interface Spans

Throws:

IOException

doc

public int doc()

Description copied from interface: Spans

Returns the document number of the current match. Initially invalid.

Specified by:

doc in interface Spans

start

public int start()

Description copied from interface: Spans

Returns the start position of the current match. Initially invalid.

Specified by:

start in interface Spans

end

public int end()

Description copied from interface: Spans

Returns the end position of the current match. Initially invalid.

Specified by:

end in interface Spans

score

public float score()

Description copied from interface: Spans

Returns the score of the current match. Initially invalid.

Specified by:

score in interface Spans

collectTerms

public void collectTerms(Set terms)

explain

public Explanation explain()

Description copied from interface: Spans

Returns an explanation of how the score was arrived at. Initially invalid.

Specified by:

explain in interface Spans